Hydraulic slack adjuster



March l0, 1931. c.vF. KETTERING 1,795,865

HYDRAULIC sLAcK l' unJUs-r'n Filed May 21, 1927 Patented Mar. 1'0, 1931 UNITI-:D STATES PATENT ori-lcs CHARLES F. KETTERING, OF DAYTON, OHIO, ASSIGNOP. TO GENERAL MOTORS RE- SEARCH CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION F DELAWARE HYDRAULIC SLACK ADJUSTER Appucation mea nay 21,

This invention relates to engines of the l type in which the crankshaft is replaced by a cam provided with two or more lobes and the their lower ends engaging the cams.

connecting rods have anti-friction rollers at In the caseof four-cycle internal combusti-on engines, this construction possesses .the advantage 'that one or more power strolges of each piston may belobtained` during a single revolution of the cam shaft. One of the problems of design presented by this kind of engine is that of maintaining the connecting rod rollers in engagement with the cam at all times. Owing to the inertia of the parts, their contraction and expansiones a result of temperature changes, and the use of springs having natural periods of vibration near the driving l range, it is practically impossible with a purely mechanical gear to avoid considerable lash. lWhen lash exists, the action of the engine will be unsatisfactory, particularly at high speeds, because of irregularity in the movement of the piston. The engine will also be noisy because of the impact of the rollers on the cams.

As a solution of this problem, I propose to employ hydraulic mechanism for maintaining the connecting rods atall times in engagement with thecams. This mechanism may take the form of an hydraulic chamber so loc-ated as to resist thel movementof'the rollers away from the cam shaft, The cham'- ber may be provided with a relatively movable wall continuously urged outwardly by a spring and may be connected with a supply of lubricant, the connection being equipped with a valve so that in the event of leakage of oil from the chamber or the contraction of the parts of the engine as a result of cooling, additional oil will be drawn into the chamber to take up the lash which would otherwise develop.

In the drawing, the figure is a sectional view thru a portionof a cam type engine showing y invention applied thereto.

2 indicates a portion of the crankcase of an engine having cylinders 4 radially arrange-d. istons 6 provided with connectlng rods 8 reciprocate in' the cylinders and the lower ends of the connecting rods are provided with 1927. Serial No. 193,253.

rollers 10 engaging a two-lobed cam 12 mounted on the engine shaft 14. To the rollers are pivoted arms 16 and 18 respectively, these arms having a colnmon fixed pivot at 20. is connected by link 22 a piston 24 reciprocating in cylinder 26 formed in or secured to the upper end of the arm 18. 'ithin the cylinder 26 is arranged a coil spring 28 which tends to separate the piston and cylinderand -to thereby causexhe arms 16 and 18`to swing but I have illustrated conduit 30 leadingv from a suitable oil reservoir, such as the crankcase, passing centrally thru the pivot 20A and then connecting with the cylinder- 26. The purpose of passing the conduit 30 through the pivot- 20 is to permit the use of rigid conduit rather than flexible conduit. for supplying oil to the hydraulic chamber 26. A non-return valve 32 may be. provided at the point of connection 'with the cylinder. The oil in conduit 30 may be under the pressure supplied by t-he usual engine oil pump.

The operation of the engine is as follows Upon rotation of the shaft 14, the pistons with their connecting rods vwill be reciprocated back and forth in the cylinders, each piston completing a cycle of movement in one revolution ofthe shaft so that there is one power impulse lper piston during each revolution. As previously described, the spring 26 urges the arms 16 and 18vin a direction to cause the rollers 10 to at all times engage the periphery of the cam. Movement of the rollers away from the cam is resisted by the-body of oil contained in the cylinder 26. In certain positions of the cam,

'lo the upper end of the arm 16 resulting contraction of the hydraulic chamber w11l cause the oil to Ybe forced outwardly between thev cylinder 26 and piston 24. A similar action will take place upon the expanslon of the parts of the gear as a result of warming up of the engine. Upon eX ansion of the hydraulic chamber at other points in the cycle, or as a result of the contraction of the parts, oil will be drawn into the chamber 26 thru the conduit 30 past the valve 32 so that it is thus insured that the chamber is at all'times illed with liquid.

I claim:

1. In combination a revoluble cam, a pair of reciprocating members having parts engaging said cam, arms pivoted to said members and an hydraulic chamber interposed between said arms so as to resist separation of the members from the cam.

2. In the combination as defined in claim 1, said arms having a common pivot and said hydraulic chamber being interposed between portions of said arms lying on the opposite side of said pivot from the points of engagement with said cam.

3. In the combination as defined in claim 1, and means for replenishing the supply of oil in said chamber.

4. An engine having a revoluble cam, cylinders, pistons in the cylinders, connecting rods connected to the pistons at one end and bearing on the cam at the other end, arms pivoted to said rods and an hydraulic chamber interposed between said arms for resisting movement of the arms away from the cams.

5. An engine having a revoluble cam, cylinders, pistons in the cylinders, connecting rods connected to the pistons at one end and bearing on the cam at the other end, arms centrally pivoted on a common pivot, one end of each arm being pivoted to one of said connecting rods and an hydraulic chamber interposed between the otherV ends of the arms for resisting separation of the connecting rods from the cam.

6. In the combination as defined in claim 5, said chamber being in the formof a cylinder connected to one of the arms, a piston in the cylinder connected to the other arm, and means for admitting oil to the cylinder to replenish the supply.

7. An internal combustion engine conprising a cam, cylinders, pistons in the cylinders, connect-ing rods pivoted to the pistons at one end and provided with rollers 'at the other end engaging the cam, arms lpivoted to the rods, said arms having a substantially central common pivot and spring means interposed between the opposite ends of the arms for urging the rollers in 'a direction to engage the cam.

' 8. An internal combustion engine com.- prising a cam, cylinders, pistons in the cylinders, connecting rods pivoted to the pistons at one end and provided with rollers at the other end engaging the cam, arms pivoted to the rods, said arms having a substantially central comlnon pivot, and spring means interposed between the opposite ends of the arms for urging the rollers in a direction to engage the cam, one of said lastnamed ends being provided with a cylinder, a piston in the cylinder connected to the other of said last-named ends, said spring means tending to separate said piston and cylinder.

9. In an engine, a revoluble cam, cylinders, pistons .in the cylinders having connectlng rods provided with rollers engaging the cam, levers pivoted to said rods and to each other, and means common to the levers `for yieldingly urging them against the cam.

10. An engine comprising a cam, cylinders` pistons in the cylinders, said pistons bei-ng provided with parts adapted to .follow the cam, arms each pivotally connected at one end to one of the pistons, said arms being pivoted to each other, and yielding means engaging the arms at points remote from said ends for causing the parts to yieldingly follow the cam.

11. An engine comprising a revoluble cam, cylinders, pistons in the cylinders, said pistons being providedI lwith parts adapted to follow the cam, arms pivotally connectedv at one end to the pistons, said armsbeing pivoted to each other between their ends, and yielding means reacting between the opposite ends of the arms for causing the pistons to follow'the cam.

12. An engine having a relatively revoluble cam and cylinders, pistons in the cylinders, the pistons being provided with parts bearing against the cam, and self-adjusting means connecting the pistons for causing each to at all times resist motion of the other away from the cam, said connecting means comprising oppositely acting levers and an hydraulic cushion interposed between said levers and resisting independent rotation thereof.

13. In an engine a revoluble cam, radially arranged cylinders, pistons in the cylinders having portions engaging the cam, means connecting the pistons and adjustable in response to variations in contraction and expansion of the cooperating parts for .causing each to at all times resist movement of the other away from the cam, said means conipri'sing levers having a common pivot and means connecting the levers so as to permit con]oint rotation thereofA but resisting independent rotation thereof. e In'testimony whereof I aiiix my signature.

CHARLES F. KETTERING. 

